(Original post by -jordan-)
-88.7 doesn't work, I'm confused as to why that's the case though. It gives you a different tan value...

Maybe it's outside the domain? Was it -90<x<90 or have I remembered it wrong? Cause -247.4, which -88.7 comes from, is definitely a solution of cosx=-5/13 between -250 and 110, which I got from applying 2x-70 to the original domain

(Original post by Parhomus)
fg(x) means f(g(x)) so when you got the equation; g(x) wouldn't be 1/x^2 it would 1/x because the x in the f(x) just means the input and so g(x) could only be 1/x. I understand why it would make sense for it to be 1/x^2.

(Original post by jtebbbs)
Maybe it's outside the domain? Was it -90<x<90 or have I remembered it wrong? Cause -247.4, which -88.7 comes from, is definitely a solution of cosx=-5/13 between -250 and 110, which I got from applying 2x-70 to the original domain

(Original post by jtebbbs)
-88.7 is a solution to the equation sec(2x-70) PLUS tan(2x-70)=-0.2, maybe that's got something to do with it? Was adding the equations that you're given to find secx (i.e. cosx) wrong?

Nope it isn't wrong, they got you to find that before you even did the second part. Everyone I've spoken to did what we did. If someone can find a valid reason or explanation as to what the actual solution was I'd be grateful.

(Original post by freddy4321)
Dunno if it helps anyone but 1.3 degrees works which is what I put down, I too got -88.7 but tried it and saw it didn't work so played around with it and got 1.3 which worked.